The blood glucose concentration is an important marker for diabetes. In the determination of a blood glucose concentration, a glucose oxidase has conventionally been used. However, such a glucose oxidase is affected by a dissolved oxygen concentration and an error is caused in the measured value. Therefore, a glucose dehydrogenase which is not affected by oxygen has also been widely used recently.
As a commercially available glucose dehydrogenase which is not affected by oxygen, a glucose dehydrogenase which requires pyrroloquinoline quinone (PQQ) as a coenzyme (PQQ-GDH) is known, however, a conventional PQQ-GDH has a disadvantage that it reacts also with sugars other than glucose such as maltose and galactose.
As a countermeasure against this disadvantage, the group of the present inventors found a novel soluble GLD which requires FAD as a coenzyme from Aspergillus terreus FERM BP-08578 strain (Patent documents 1 and 2). Such a GLD has unprecedented excellent properties that it is not affected by dissolved oxygen, oxidizes a hydroxy group at the 1-position of glucose, and has a low activity (enzymatic activity) for maltose and galactose.
On the other hand, Patent Document 3 disclosed a method for decreasing the risk of coronary artery diseases by administering 1,10-phenanthroline to a patient of diabetes, especially Type-II diabetes. Patent Document 4 discloses a method for arresting hemorrhage by inhibiting ADAM8, an agent of promoting blood circulation and inhibiting thrombus formation, or a method for inhibiting blood clotting by increasing said agent. 1,10-phenanthroline is listed as an agent for inhibiting ADM8. Patent Document 5 discloses an invention relating to a tube for collecting blood, characterized by comprising 1,10-phenanthroline and the like for inhibiting the decomposition of proteins in a blood sample. Accordingly, when the determination of glucose is performed by using as a sample the blood obtained from a diabetes patient who has been treated with the methods disclosed in Patent Document 3 or 4, or by using as a sample the blood kept in the tube disclosed in Patent Document 5, there will be a possibility that a false blood glucose value might be determined due to the existence of 1,10-phenanthroline in said blood causing a risk that a wrong treatment would be adopted for the patient, if an enzyme contained in a device for the determination of blood glucose is affected by 1,10-phenanthroline.    Patent document 1: WO 2004/058958 pamphlet    Patent document 2: WO 2006/101239 pamphlet    Patent document 3: WO 2003/077901 pamphlet    Patent document 4: JP 2010-275216 A    Patent Document 5: Japanese Patent No. 4496407